1. Field of the Invention
This invention relates to a method and apparatus for coating powder material, such as soybean flour, sesame or green laver, onto food pieces (for example, dumplings, such as rice dumplings mixed with mugwort or covered with bean jam, or rice balls) such that the food pieces are coated by the powder.
2. Description of the Related Art
One type of prior-art coating machine includes a mechanism which is disposed over a conveyor for depositing powder material onto the upper or side surfaces of food pieces conveyed on the conveyor. A problem with these machines is that the bottom surfaces of the food pieces cannot be coated with the powder material.
An improved coating method which addresses the above-mentioned problem is disclosed, for example, in Japanese Patent Publication No. 62-46149. The method comprises the steps of continuously conveying and feeding both food pieces formed in a given shape and grain flour into a drum, and rotating the drum to continuously coat the food pieces with the grain flour within the drum, wherein both the food pieces and the grain flour are rolled together by means of baffle rods in the drum so that the food pieces are coated with the powder.
In the above-mentioned prior-art coating machine, grain flour and food pieces are rolled together to coat the food pieces with the powder, and grain flour which does not adhere to the food pieces can be recovered and effectively reused. However, because adequate space within the drum is needed to coat the food pieces with the grain flour, the drum must be large, thereby occupying a considerable space.
Also, the drum is tilted so its outlet is positioned lower than its inlet in order to discharge the coated food pieces. This difference in height between the inlet and outlet causes some problems. When supplemental manual operations are performed, the working environment around the lower outlet is not good, especially over a long time.
Further, when the production line including the coating drum is used to produce food products which do not need a powder coating, the drum must be removed from the production line, which requires significant effort and time.